Damping is the absorption of mechanical energy by a material in contact with a source of mechanical energy. A convenient measurement of the damping is the determination of the tan .delta. of the damping material. In common practices, the tan .delta. of a material can be adjusted by varying, broadening or adding to the glass transition peak at the desired temperature range.
Several specific materials have been employed for damping. U.S. Pat. No. 5,494,981 teaches a composition containing resins that are cured in sequential fashion by using a single catalyst, which is a Bronsted acid, that activates an epoxy resin component, then activates cyanate trimerization into poly(triazines). The composition provides a damping (glass transition) peak around 100 E C. The compositions disclosed in this patent are taught to be heat stable over a temperature range of about 0.degree. to at least 300.degree. C.
U.S. Pat. No. 5,008,324 teaches a composition that comprises a crosslinked elastomer and a multi-phase thermoplastic elastomeric polymer. The multi-phase thermoplastic elastomeric polymer has at least two polymeric phases including an initial linear or lightly linked polymeric phase and a second polymeric phase in the form of discrete domains dispersed within the initial polymeric phase. The initial polymer phase provides a glass transition damping peak around 10 to 70.degree. C.
U.S. Pat. No. 5,225,498 teaches a damping material that includes an interpenetrating polymer network having a soft polymer component made of polyurethane and a hard polymer component made of a vinyl ester polymer. The polyurethane and the vinyl ester polymer are polymerized in the presence of one another and cured at room temperature. The interpenetrating polymer network is taught to have an acoustic damping factor in excess of 0.2 over a temperature range of from about 15 to 85.degree. C., with glass transition damping peak at about 55.degree. C.
U.S. Pat. No. 5,670,006 teaches a composition for vibration damping that includes an acrylate-containing thermoset resin that includes an interpenetrating network of polymerized epoxy monomer and polymerized acrylate monomers. The epoxy-acrylate thermoset resin is taught to have a glass transition temperature in the range of about -2.degree. C. to about 200.degree. C. at 1 Hz.
It is particularly desirable to develop high damping additives that are effective over a wide range of temperatures and frequencies without involving glass transition peaks. Also, it is important to blend the additives with hydrogenated block copolymers to form a thermoreversible polymer gel having high damping properties.